Process for resolving petroleum emulsions



Patented Nov. 22, 1949 1 PROCESS FOR RESOLVING PETROLEUM EMULSIONS John L. Harlan, Houston, Tex., assignor, by mesne assignments, to Standard Oil Development Company, Elizabeth, N. J., a corporation of Delaware "-No Drawing.

Original application SeptemberM,

1945, Serial. No. 616,457, now Patent No. 2,454,382, November 23, 1948. Divided and this application May 2.6, 1948, Serial No. 29,403

The present invention is directed to a method for resolving water-in-o'il emulsions;

This application is 'a division of copending application Serial No. 616,457, "filed September f4, 1945, now Patent No. 2.454.382 issued November'23, 12948.

. In the petroleum'ind-us'try water-in-oilemulsions are frequently encountered both in the new and in the refinery. Theseemulsions. comprise fine droplets of naturally-occurring waters or brines, dispersed in a more or less permanent state throughout 'theoil which constitutes the continuous phase of the emulsion. They are obtamed' from producing wells: and: from the. bottoms of oil storage tanks, and are commonly referred to as cut oil, roily oil, emulsified oil, and bottom settlings.

The object of this invention is to provide a novel, inexpensive and e'ificient process for separating emulsion-s of the kind referred to-into their component parts of oil and water orbrine.

Briefly described, thisprocess consists in subii-ecting a petroleum emulsion of the water-irrci-l type to the action of a treatin agent or demulsifyin agent of the kind hereinafter described, thereby causing the emulsion to break down and separate into its component parts of oil and water or' brine, when the emulsion is permitted to remain in a quiescent state after treatment, or is subjected to other equivalent separatory procedures.

Theztreatingyagent or demulsifying agent. used in the; process-:ofthe present invention comprises a=mtrogenousa derivative of a petroleum sulpiionicrracid .bodm. specifically such sulphonic iazci'ctbodies ;a-s-a-re derived frompetroleum. boiling the lubricating. :oil. range; These nitrogenous derivatives are prepared by reacting petroleum sulphonic' acid bodies with concentrated nitric acid. The product of this reaction is *2: nitroderivativeof the sulphorric acid body. *These 'ril-tro derivatives maybe readily reduced treatment with nascent hydrogen to amino derivatives. When the nitro derivatives are reduced in an alkaline medium, the nitro sulp'honate-is first reduced to an amino sulphonate and then two molecules of the amino sul'phonate condense through the amino radicals with the elimination of ammonia to form a molecule containing two 'sulphonic acidbodies connected to a nitrogen atom. The hydrogen atoms of the amino groups may be replaced by other radicals or-substituentsto produce a widevariety of prodacts;

These nitrogenous derivatives may be used in the form of their sodium or "ammonia salts or in the form of their calcium, cyclohexylamine or similar oil soluble salts. The nitrogenous sulphonic acid body may be esterified by monohydric or polyhydric alcohols. In the latter case free hydroxyl groups of the polyhydric alcohol may be further esteriiied with other large orgamc molecules having demulsifying power, such as Diels-Alder condensation products.

These nitrogenous derivatives of sulphonic acid bodies are particularly effective on the stubborn emulsions which collect in the bottoms of oil storage tanks. Some of these emulsions are very stable and are not capable of resolution by a great many o'f'the commercial demulsifying agents. In general the amino derivatives are more effective than the nitro derivatives, which in turn are more efiective than the sulphonic acid bodies per se.

In the following examples are described some of the demul'sifying agents contemplated for use in the present invention:

acidified with grams of concentrated sulphuric acid. The sodium sulphonatehad the following approximate analysis: 27.6% sodium sulphonate', 124% sodium sulphate, 15.5% water and 56.6% oil. The acidifiedsulphonate was heated to 132 F. while stirring. Stirring was stopped andthe mixture allowed'tosettle 30 minutes. After settling, 104 gramsof acid water (69 ml.) were withdrawn and discarded. The acid water still contained the sulphuric acid,:sodiumsulphate and some iron impurities; The sulphonic acid layer (996 grams) was then treated with 170 grams of concentrated (70%) nitric-acid ml.). The acid was added slowly in '10 m1; portions. The first 20 cc. of acid addedsover a 20 minute period caused the temperature to rise from 90 F. to 126 F. with the production of a slight foam. After the foam subsided, six 10 ml. portions of nitric acid were added slowly, making a total of 80 ml. acid. The temperature remained between about 130 to F. On stirring, the reaction of the nitric acid continued as indicated by a rise in temperature and foaming. After stirring for ten minutes, 40 m1. of nitric acid was added slowly making a total of 120 ml. acid or grams. A slight rise in temperature occurred. After several hours of stirring the reaction mixture was heated to 160 F. At this higher temperature a separation into three phases occurred, (1) an oil layer amounting to 460 grams, (2) a nitro sulphonate layer amounting to 640 grams, and (3) an acid Water layer amounting to 64 grams. The oil layer and the acid Water layer were withdrawn and discarded. The nitro sulphonic acid layer was then neutralized with about 128 grams of 50% NaOI-I solution. This sodium salt of the nitro sulphonate is an excellent demulsifier for crude oil water-inoil emulsions. It is particularly suited for the resolution of the aged tank bottom emulsions which collect in the bottom of oil storage tanks. It is more effective than the original sulphonate used on such emulsions.

mm ple II amino radicals. Stirring was discontinued after the evolution of ammonia gas stopped. The reduced nitro sulphonate was decanted into a separatory funnel. The unreacted zinc was washed with isopropanol and the washings combined with the amino sulphonate. The amino disulphonate was then acidified with hydrochloric acid to remove the zinc ion. The amino di-sulphonic acid was then washed with small portions of saturated salt solution and then neutralized with caustic solution. The alcoholic solution of the amino di-sulphonate was allowed to settle to precipitate the inorganic salts. The alcoholic solution was then evaporated to a concentration of 35% amino di-sulphonate. This amino di-sulphonate is particularly well adapted to the resolution of crude oil emulsions such as encountered The nitro sulphonate prepared in accordance amino sulphonic acids were then neutralized with 50% sodium hydroxide to a phenolphthalein endpoint and diluted with 100 ml. 91% isopropanol. The inorganic salts were allowed to settle and the amino sulphonate layer decanted. This amino sulphonate is an excellent demulsifier for tank bottom emulsions and live oil emulsions. It is more effective than the original sulphonate or the nitro sulphonate.

Example III Five hundred grams of a 50% aqueous solution of substantially pure sodium sulphonate derived from '75 Stock Phenol Extract Acid oil was nitrated with 300 ml. of 70% nitric acid. The nitric acid was added slowly while stirring with a mechanical mixer. The reaction was vigorous after the addition of the first 120 ml. of acid. The balance of the acid was added slowly as the foam produced by the initial reaction subsided. Heat was liberated and nitric acid fumes were given off at the point of initial reaction. After the reaction of nitric acid and sulphonate was substantially complete, the added water was withdrawn and discarded. Thenitro sulphonate layer was neutralized with 40% caustic solution. The sodium salt of the nitro sulphonate was then diluted with isopropanol and allowed to settle for several days. The clear alcoholic solution of nitro sulphonate was then decanted from the inorganic salts and evaporated to a concentration of 61% nitro sulphonate by weight. This material is an excellent demulsifier for crude oil emulsions.

Example IV One hundred grams of nitro sulphonate as prepared in Example III was reduced to an amino sulphonate by means of zinc dust and sodium hydroxide solution. The sample of nitro sulphonate was placed in a one liter flask equipped with a mechanical stirrer. 50% sodium hydroxide solution and 50 grams of zinc dust were added. The mixture was stirred. During the first part of the reaction only hydrogen was given off. In the latter part of the reac- Two hundred milliliters of tion, ammonia gas was given off. This evolution of ammonia gas indicated a condensation of the in the Conroe field (Montgomery County), Texas. Example v Seventy-five grams of anhydrous oil free sodium sulphonate derived from the treatment of medicinal white oil stock with fumingsulphuric acid was diluted with an equal part of distilled water and then nitrated with 25 mlof 70% nitric acid. The reaction of nitric acid and sulphonate did not take place readilyi The nitric acid caused a salting out of the inorganic salts and no exothermic reaction occurred. The aqueous acid was allowed to settle and it was then withdrawn and discarded. Fifty milliliters of concentrated nitric acid was then added. This mixture was stirred under a mechanical mixer for three hours, during which time the nitration took place very slowly. The reaction was assisted by the application of external heat to maintain a temperature of F. At this temperature nitration took place very smoothly. After three hours the mixture was allowed to settle. The free acid which separated was pipetted off and discarded. The acid nitro sulphonate was then neutralized with 40% caustic solution and then diluted with a volume of 91% isopropanol. The inorganic salts were allowed to settle. The clear sodium saltof the nitro sulphonate in alcoholic solution was then evaporated to a concentration of 56.5% by weight. This material is an excellent material for the resolution of crude oil emulsions.

Example VI In order to demonstrate the effectiveness of the agents of the present-invention, comparative tests were made on the effectiveness of these agents, as well as a standard commercial agent and some of the sulphonates from which these agents are prepared. The emulsion employed in these tests was a tank bottom emulsion resulting from storage of Illinois Basin Crude, Martinsville Tank Farm, Ohio Oil Company, a very difiicult emulsion to dissolve. The agents employed are designated in the following table as A, B, C, D, E and F. p

Agent A was a commercial compound containing 68 weight per cent of petroleum sludge-sulphonate.

Agent B was the nitro derivative. the manufacture of which "'described*-in Example III.

ilt-was an alcoholic solution containing 61 weight per cent of the nitro derivative.

Agent ,C was the .base snlphonaterecited in Example "V" from whichthe' nitroderivative was prepared. It was an oilsolution containing 70 t weight per "cent of the sulphonate.

Agent: D- was thenitro derivative, the manu- AgenttE-was-the amino:.di:-sulphonate, the pre- :paration of .which.is describedin Example IV and was'xinltheform of. an-alcoholic solution containing 46 weight per cent of the di-sulphonate.

Agent F was the base sulphonate employed for the preparation of the nitro derivative in Example III and was in the form of an oil solution containing 46 weight per cent of the sulphonate.

In performing these tests, the customary procedure for testing the efiectiveness of demulsifying agents was as follows:

100 ml. of the tank bottom emulsion was poured into each of seven 6-ounce prescription bottles. The treating agent was pipetted into each bottle after it has been warmed to 100 F. The bottles were capped and given 100 vigorous shakes to disperse the chemical throughout the emulsion. The bottles were placed in a water bath and the temperature allowed to increase to 115 F. in 15 minutes. At this time observations were made on the condition of the emulsion. Subsequent observations were made at 45 minutes, four hours and seven hours, as listed in the table. After these observations, small samples were taken for centrifuge tests. The oil was diluted with an equal volume of benzene in the centrifuge as is customary in oil field practice. After this dilution the bottle was shaken vigorously and samples of the entire contents of each bottle were taken for centrifuge tests.

The data obtained in these comparative tests were as follows:

sionsfithe problem I is not: only to :produce :pipe line oil, but it is equally important? to' dispose-cf thesludge-v/hich accumulates tin the tanks. JEX- -a-mp1es B,-'D and'E indicate that the agentsof the present invention practically :eliminate this sludge problem.

'lhese demulsifying agents are used in the treatment of emulsions the manner and in amounts customary in the art. In general, one part'of demulsifying agent will be used for each 6000to -l0,000'parts of live oil emulsion and for each 1000 to 2000 parts-of aged tank bottom emulsion. These demulsifying agents may be used alone or in conjunction with other known demulsifying agents. A particularly suitable combination is the sodium salt of a nitrogenous derivative of a petroleum sulphonic acid body and the calcium or cyclohexylamine salt of the same or another nitrogenous derivative of a petroleum sulphonic acid body. These two types have different solubilities, the first type being more water soluble and the second type being more oil soluble. The combination of the two gives a highly effective demulsifying action.

The nitration according to the present invention is ordinarily carried out at a temperature between about F. and 160 F. The nitric acid appears to react with the sulphonic acid body by splitting ofi a fraction of the hydrocarbon molecule, or side chain, and combining with the molecule at this point. This mechanism is suggested by the production of fatty acid lay-products. The sulphonic acid group is not split oil of the molecule. Analytical tests have failed to indicate any free sulphuric acid group resulting from the action of the nitric acid on the sulphonic acid bodies. It is believed that small amounts of nitro paraffins are produced by side reactions, but the nature of these side reactions has not been fully determined.

The method of preparing amino di-sulphonate disclosed herein, particularly in Example IV, is specifically claimed in my copending application Serial No. 616,456, filed September 14, 1945.

Demulsifying Agent D E Blank Ml. of 10% by V01. aqueous solution of reagent added at F. to 100 ml. emulsion.

After 15 min. at F. ml;

Water After 4 hours temperature raigeii to F.:

Centrifuged Samples Middle on Layer:

It will be noted that the oil obtained from the middle oil layer was considered to be of pipe line specification in all cases excepting the blank.

.However, in the resolution of tank bottom emul- 75 The nature and objects of the present invention having been fully described, what I desire to claim is:

1. A process for breaking a petroleum emulsion JOHN L. HARLAN.

8 REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Reddish Feb. 18, 1930 Oberlin Aug. 3, 1937 De Groote et al Apr. 11, 1939 De Groote Feb. 1 1941 Thompson Apr. 15, 1941 Griesinger et al. June 10, 1941 Angruss et a1 Dec. 26, 1944 Harlan Nov. 23, 1948. 

